抑制REPL中原子保持的数据的打印？ （或ref，代理，...） [英] Suppress the printing of the data an atom holds in the REPL? (or ref, agent, ...)

问题描述

以下是完全有效的Clojure代码：

The following is perfectly valid Clojure code:

(def a (atom nil))
(def b (atom a))
(reset! a b)

但是，在REPL中使用这样的东西很烦人：REPL将尝试打印此类引用的内容，只要你键入a或

However, it is annoying to work with such things in the REPL: the REPL will try to print the content of such references whenever you type a or b, and will, of course, generate a stack overflow error pretty quickly.

因此，有任何方法来控制/更改atom / refs /代理的打印行为。 Clojure？某些类型的循环检测将是很好的，但即使完全抑制deref'ed内容也是非常有用的。

So is there any way to control/change the printing behaviour of atoms/refs/agents in Clojure? Some kind of cycle detection would be nice, but even the complete suppression of the deref'ed content would be really useful.

推荐答案

您可以说

(remove-method print-method clojure.lang.IDeref)

可以从 print-method 中删除​​对derefable对象（Atoms，Refs等） ，使其打印如下：

to remove special handling of derefable objects (Atoms, Refs etc.) from print-method, causing them to be printed like so:

user=> (atom 3)
#<Atom clojure.lang.Atom@5a7baa77>

或者，您可以添加更具体的方法来禁止打印内容一些特定的引用类型：

Alternatively, you could add a more specific method to suppress printing of contents of some particular reference type:

(defmethod print-method clojure.lang.Atom [a ^java.io.Writer w]
  (.write w (str "#<" a ">")))

user=> (atom 3)
#<clojure.lang.Atom@4194e059>

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